Test 3 Fall 2008 - MIBO3500 Exam 3 Fall 2008 40...

MIBO3500 Exam 3 Fall 2008 40 pts (Recorded as percentage) Multiple Choice -1 pt each 1. An organism has experienced a mutation in its DNA. The wild type DNA sequence reads: 3’ GAG 5’ while the forward mutation reads 3’ GGG 5’. Sequencing of the gene indicates that the number of nucleotides in the gene has neither increased, nor decreased. Using this information and your knowledge about mutations, which of the following mutation types has occurred? a. nonsense mutation b. missense mutation c. frameshift mutation d. silent/neutral mutation 2. What is the function of neuramidase (NA)? a. Aids in the specificity of the HIV virus to bind to and infect its target cells. b. Serves to help penetrate through mucous layers. c. Produces a viral cDNA strand from a –ssRNA strand so that provirus formation can occur. d. Causes the formation of a provirus, and initiates lysogenic viral reproduction. 3. Which of the following types of genetic transfer can occur during infection by a virus which incorporates its genome into the host cell’s chromosome? a. Hfr x F- conjugation b. Conjugative transposition c. Specialized transduction d. Transformation 4. During the productive viral replication cycle, during which of the following statements is TRUE ? a. Endolysins produced during an early transcription phase act o degrade host cell DNA. b. Proteins necessary for genome replication are transcribed and translated at the same time as those necessary for maturation and assembly of new viruses. c. The genetic code for virus-specific polymerase production is found within the host cell’s DNA. d. The presence of viral peplomers regulates the ability of a virus to attach to a target host cell. 5. _____ represents a mechanism of entry by enveloped viruses into a host cell, while ____ is the most common type of exit for these same viruses. a. Direct penetration; cell lysis b. Endocytosis; budding c. Membrane fusion; cell lysis d. Direct penetration; budding 1

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MIBO3500 Exam 3 Fall 2008 40 pts (Recorded as percentage) 6. Which of the following is characteristic of the clinically latent (asymptomatic) stage of HIV infection? a. Transcription and translation of viral proteins result in a titer elevation of HIV antibodies. b. HIV incorporates as a provirus and undergoes lysogenic replication in the T lymph cells. c. A depletion in immune cells results in symptoms such as abdominal pain and chronic thrush. d. Virus particles are replicated quickly and accumulate in the blood. 7. Genetic exchange which requires direct cell contact between two bacterial cells has occurred and successfully transferred some random chromosomal DNA from the donor. The newly transferred chromosomal DNA has been identified as being on a plasmid. An inspection of the recipient strain (after the successful exchange) shows the presence of a sex pilus. However, the recipient strain was originally incapable of sex pilus production.

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